Semiconductor workpieces are often implanted with dopant species to create a desired conductivity. For example, solar cells may be implanted with a dopant species to create an emitter region. This implant may be done using a variety of different mechanisms. The creation of an emitter region allows the formation of a p-n junction in the solar cell. As light strikes the solar cells, electrons are energized, creating electron-hole pairs. The minority carriers, which are created by the energy from incident light, are swept across the p-n junction in the solar cell. This creates a current, which can be used to power an external load.
Solar cells are often arranged in arrays, where one or more solar cells are arranged in parallel. When all of the solar cells are illuminated, all generate current. However, when one of the cells is shaded, that cell will not produce any current. Furthermore, the shaded solar cell may experience reverse current, where, due to the voltage applied on either side of the p-n junction, current flows through the solar cell in the reverse direction. This may have detrimental effects on the entire solar cell array by heating small regions of the solar cell to excessive temperatures.
Reverse current is a known phenomenon that results from the configuration of the solar cell. However, the thermal effect of the reverse current may be exacerbated by defects or other anomalies in the manufacturing process. For example, reverse current can be increased by imprecise doping of the solar cell or by poor metallization control during the manufacture of the device.
Therefore, a method that improves the manufacturing process associated with solar cells, and particularly reduces reverse current, would be beneficial.